Enantioselective Synthesis of Tetrahydropyrano[3,4-b]indoles: Palladium(II)-Catalyzed Aminopalladation/1,4-Addition Sequence

A novel palladium(II)-catalyzed cyclization of aniline-tethered alkynyl cyclohexadienones is reported. This reaction offers an atom-economical and redox-neutral access to various cyclohexenone-fused tetrahydropyrano[3,4-b] indoles with high yield and excellent enantioselectivity. Remarkably, this work represents the first example on a transition-metal-catalyzed asymmetric intramolecular aminopalladation/1,4 addition sequence.